Adjustable loading ramp



March 30, 1965 M. R. PENNINGTON 3,175,238

ADJUSTABLE LOADING RAMP Filed March 30, 1962 6 Sheets-Sheet 1 Fig.6.

March 30, 1965 M. R. PENNINGTON ADJUSTABLE LOADING RAMP 6 Sheets-Sheet 2Filed March 50 1962 March 3G, 1965 M. R. PENNINGTON ADJUSTABLE LOADINGRAMP 6 Sheets-Sheet 5 Filed March 30 1962 E y m Umm M M wm y S. m2 l2. jme lll@ f mms. IIWMMMWIA mm y Wuhnhh @.N

March 30, 1965 M, R. PENNINGTON 3,175,238

ADJUSTABLE LOADING RAMP Filed March 30, 1962 6 Shee'cs-Sheerl 4 FIG.8

March 30, 1965 M. R. PENNINGTON 3,175,238`

ADJUSTABLE LOADING RAMP 6 Sheets-Sheet S Filed March 50, 1962 alg)`March 30, 1965 M. R. PENNINGTON 3,175,238

ADJUSTABLE LOADING RAMP Filed March 30, 1962 6 Sheets-Sheet 6 L Q "l 9s'282 286 28B [284 m ---m 262 22g- 23e] C540 24) 23s 1k. la

ZIO)

FIGJI United States Patent O 3,175,238 ADJUSTABLE LDADlNG RAMP MargaretRedick Pennington, Pittsburgh, Pa., assigner to .lames H. Elkus,Pittsburgh, Pa. Filed Mar. 30, 1962, Ser. No. 183,806 7 Claims. (Cl.14-71) This invention relates to improvements in loading ramps andrelates in particular to ramps which may be extended or retracted andwhich may be employed as a self supporting or free floating loadingramps.

In the handling of materials in present day commerce, it is commonpractice to employ loading ramps at docks or doorways where trucks and/or railway cars are loaded or unloaded. These ramps compensate for thevariations in height between the dock level and the truck or car floorlevel. The position of the vehicle floor in respect to the loading dockis dependent on the skill of the driver, the size of the vehicle and therelative height of the vehicle in respect to the dock.

Conventional mechanically or hydraulically operated loading rampsconsist of rectangular shaped platforms that are hinged along one edgeto stationary platforms. The free edge of these platforms may beelevated or lowered to compensate for truck floors of varying elevation.These ramps are generally provided with an apron or tongue which extendsbeyond the free edge of the ramp and which is positioned to rest on theiioor of the truck. Neither the free edge of the ramp nor the extendingapron of the conventional ramp can be positioned horizontally.

The loading ramp of the present invention is one which not only may beraised and lowered but is capable of horizontal adjustment of the freeedge of the ramp.

Ramps have been devised that may be extended or retracted horizontallyas well as raised and lowered; however, most operate on the principle ofa platform mounted on a frame or ramp which may be raised or lowered,the platform may be extended beyond the ramp or frame to rest or floatbetween the floor of the truck and the ramp or frame. Consequently theremay not only be a deviation in levelness between the dock surface andthe supporting ramp or frame but also between the frame or ramp and thefioating extended platform. Such considerations are of considerableimportance because fork trucks and other loading vehicles must traversesuch ramps while carrying heavy loads and any unnecessary deviations inthe continuity of the platform over which they must travel greatlyinhibits their progress.

Also, loading ramps may be classified as oating or self supporting. Thefloating ramp or extensible plan form is supported at one end by theloading dock or supporting platform or frame if the ramp is extensibleand at the other end by the truck fioor where the lip or extendedportion of the ramp cornes to rest. With this arrangement the rarnp issaid to be iioating between the truck oor and the dock or othersupporting members.

On the other hand a self supporting loading ramp is one in which the lipof the ramp may touch the truck door but the ramp itself is whollysupported by its own supporting members.

There are, of course, advantages and disadvantages to each type of ramp.For example, the self supporting ramps may be utilized to elevate heavyloads to a truck floor or platform that is higher than the dock surfaceand the ramp does not add its weightV to a truck or trailer floor so asto depress the springs of such vehicles and cause unnecessary unevennessor tilting of the truck or trailer. The floating ramp iioats with thetruck floor so that when the truck licor is depressed due to the weightof the materials being loaded, the ramp follows the truck floor whilethe self supporting ramp must be adjusted to compensate for a lowertruck iloor surface by mechani- 3,li5,238 Patented Mar. 3G, 1965 icecally lowering the ramp. Also, if the floating ramp is segmented, eachsegment will follow a rising or falling truck fioor so that if the truckfloor is tilted in any manner the individual segments will compensatefor the unevenness and the lip of each segment will rest on the truckfloor in spite of the fact some of the segments will be furtherdepressed than others. For example if the truck floor is depressed onits left side further than on its right side, in respect to itspositioning in front of the ramp, only the right side of a non segmentedramp will contact the truck floor and a considerable drop will existbetween the ramp lip and the truck door on the left side of the ramp.However, if the ramp is iloating :and segmented each segment willcontact the truck floor so that materials can be more easily transportedover the ramp surface to and from the truck.

The ramp of the present invention is extensible and retractable butprovides a rigid surface from the dock edge to the lip of the ramp ineither the extended or retracted position so that there are nounnecessary deviations between the dock surface and the truck iloor.Also, the present ramp embodies features that enables one to utilize theramp as either a self supporting ramp or as a free fioating ramp.Additionally, the present ramp is segmented so as to enable one to takeadvantage of free floating and segmented features as well as the selfsupporting, nonsegmented features of loading ramps.

lt is therefore an object of the present invention to provide a loadingramp that may be extended or retracted but which is rigid from the dockedge to the extended lip of the ramp.

it is also an object of the present invention to provide a loading rampwhich may be used as a free floating or a self supporting ramp.

It is a further object of the present invention to pro vide a loadingramp which may be used as a segmented free oating loading ramp or as arigid self supporting ramp.

A still further object of the present invention is to provide a loadingramp that may be extended or retracted but which is rigid from the dockedge to the lip of the ramp and which also may be used as a freefloating loading ramp or as a self supporting loading ramp.

A still further object of the present invention is to provide a loadingramp that may be extended or retracted but which is rigid from the dockedge to the lip of the ramp and which also may be used as a segmentedfree floating extensible loading ramp or as a rigid self supportingextensible loading ramp.

Other objects and advantageous features may be best described by thefollowing specification and drawings wherein:

FEGURE l is a bottom perspective view showing a ramp constructed inaccordance with one embodiment of the present invention.

FG. 2 is a top plan view of a broken away portion of the ramp of FlG. lshowing segments me, 12j and 12g and a portion of segment 12d of theramp 10.

FIG. 3 is a bottom plan View of the broken away portion of the ramp ofFIG. 1, also showing segments 12e, M, and iZg plus a portion of segment12d. K

FG. 4 is a side elevation View of the loading ramp of PEG. l, shown inits horizontal at rest position (the dock pit being shown in crosssection).

FIG. 5 is a side elevation view of the ramp of FIG. 1 shown in anextended position (the dock pit being shown in cross section).

FlG. 6 is a cross sectional view of segment 12g of the ramp as takenalong the line VI-VI of FIGURE 2.

FIG. 7 is a cross sectional view of segment 12g of the ramp it) takenalong the line VII- VII of FIGURE 2.

FIG. 8 is an end elevation view of the loading ramp of FIG. 1 shown inits at rest position (as in FIG. 4).

FIG. 9 is an end elevation view of the loading ramp of FIG. l shown inits free floating position.

i FIGS. 10 and 11 are schematic representations of an electrical controland hydraulic power systems to operate the ramp of FIG. 1.

' In the drawings there is shown a loading ramp 18 positioned within adock pit 11 (see FIGS. 4 and 5) which consists of a depression withinthe loading dock 28. The pit 11 is lined on either side with angle curbs13. The loading ramp 10 comprises a number of individual segments 12(12a, 12b, 12e, 12d, 12e, 12]C and 12g). Each segment 12 is individuallyhinged as shown at 14 (FIGS. 1-5) to a rear angle frame 16,appropriately imbedded in the rear of the concrete dock to permitpivoting of each segment 12 and allowing proper positioning of the freeend of the ramp 10. FIG. 4 shows the ramp 10 in its horizontal at'restposition in respect to the loading surface 18 of dock 20. Each of thesegments 12 are formed of beam members 28 and sleeve shaped members 38.The members 28 are hinged to the dock 28 as shown at 14 and the sleeveshaped members 38 are disposed to slide over and telescope outwardly onmembers 28. It should be noted that the ramp segments 12C and 12e arethe segments shown by FIG. 1 to carry the power means (rams 26) forextending and retracting the extensible features of the ramp 10.

FIG. 6 is a cross sectional view of the ramp segment 12g taken alongline VI-VI of FIG. 2. It is understood that each of the segments areconstructed in a substantially identical manner, the only exceptionsbeing the attached power means such as rams 26 which are attached tosegments 12C and 12e and the bumper stabilizing arms 112 which areattached to segments 12b and 12j. The power means and bumper stabilizingarms may, of course, be attached to any of the segments 12. Preferablythere is a balanced relationship. For example, if ram 26 is installed onany but the center segment 12d a balancing ram would preferably beinstalled on the corresponding segment on the other side of the centersegment.

The cross section of FIG. 6 shows that members 28 of segment 12g isformed of a deck plate 30 attached to an I beam 32. As shown by FIG. 3the deck plate 30 terminates as shown at 31 while I beam 32 projectsinto the sleeve shaped member 38.

Positioned as telescoped over beam members 28 are the rectangular sleeveshaped members 38. FIG. 7 is a cross sectional view of the sleeve member38 of segment 12g of FIG. 2 taken along the line VII-VII thereof. Sleevemembers 38 are shown to be formed with a deck plate 48, side members 42and 44 and a bottom plate 46. Deck plate 40, side members 42 and 44 andbottom plate 46 are all attached to form sleeve shaped member 38. It isto be noted that side members 42 and 44 extend slightly beyond bottomplate 46 as shown so as to form slide surfaces 48 Whose function will beexplained hereafter. FIG. 7 shows I beam 32 of member 28 positionedwithin sleeve shaped member 38. There is also shown angle bars 58 and 52which are attached to either side of flange 34 of I beam 32 and whichprovide bearing surface upon which side members 42 and 44 and deck plate48 of sleeve member 38 may slide. Likewise angle bars 54 and 55 areshown attached to either side of the bottom flange 36 of I beam 32 so asto space flange 36 from bottom plate 46 and side members 42 and 44 ofsleeve shaped member 38 and provide suitable slide surfaces betweenmembers 28 and sleeve members 38. Angle members 50, 52, 54 and 55 onlyextend from the end of deck plate 3i) (at 31) to the end of members 28since this is the only area in which sleeve shaped members 38 projectover and slide upon the members 28 of the segments 12a-12g. Since thesleeve members 38 slide -in and out on tube members 28 the arrangementof slide angle bars 5G, 52, 54 and 55 effectively reduce lfriction byproviding a reduced sliding surface and hence, effect a reduction in theCil friction that would occur if deck plates 30 and 48 or bottom plate46 and flange 36 were permitted to slide on one another.

Each of the deck plates 40 of sleeve members 38 are shown 'to extendbeyond the free ends of sleeve members 38 so as toform a vehicle fioorcontacting lip as shown at 56 (FIGS. 1, 4 and 5). Also, side members 42and 44 extend at an `angle to provide additional strength to lip 56 asshown at 58. End plates 60 and 62 (FIG. 1 and 4) complete the sleeveshaped structure, add strength to the member and limit the distance thatsleeve members 38 will slide over members 2S. End plates 60 and 62 areattached to sleeve members 38. Deck plates 40 overlap side members 42and 44 as shown at 45 (FIG. 7). Members 47 (FIG. 1 and 7) are attachedto either side of side members 42 and 44 and to deck plate 40 to provideadditional strength to sleeve members 38. End plates 37 (FIGS. 1, 6 and7) are attached to the back of members 28 to add strength to thisstructure. Angle plates 29 and 27 (see particularly FIGS. 1 and 6) serveto cover the exposed I beams 32 of outer segments 12a and 12g and act asa safety guard to keep the area between deck plate 3i) and the docksurface 18 clear when raising and lowering the ramp.

Deck plates 30 terminate as shown at 31 at the place where I beam 32 ofmembers 28 project into sleeve members 38 while the ramp is in itsretracted position. A cover plate 39 (FIG. 2) is attached to each of thedeck plates 40 to cover up the spaces that would appear between the Ibeam 32 of the segments 12 which would be exposed when the sleevemembers 38 are extended on the members 28. Cover plates 39 as hinged todeck plates 40, as shown at 43 (FIG. 2), so that upon the application ofweight to the ramp segments 12 the cover plate 39 will not tend tobuckle upwards and interfere with the continuity of the ramp surface.

As shown particularly in FIGS. 1, 8 and 9 each of the segments 12 arelinked together to form ramp 10 by links 64. A bracket plate 66 isattached to each of bot- 'tom plates 46 of sleeve members 38 so as toextend beneath each of the sleeve members 38 of segments 12. A pair oflinks 64 are pivotally attached on either side of each bracket plate 66by means of pivot pins 69 so that a pair of such links pivotally connecteach segment 12 to its adjacent segments. The end segments 12a and 12grequire only one pivotal connection of links 64 since there is only oneadjacent segment. In this manner the segments 12 through sleeve members38 and links 64 are linked together so as to form a single ramp unit. Aswill be shown herebelow the sleeve members 38 are linked together insuch a manner that they may slide on I beam 32 of members 2S uniformlyas a single unit but the ramp, though linked together as a single unit,is segmented so that when lips 56 of segments 12 contact an uneven truckfloor or platform, one segment 12 may be further depressed than itsneighbor so as to compensate for the unevenness (see FIG. 9).

It will be appreciated that the links 64 will not permit the segments 12to follow a vehicle floor (as shown in FIG. 9) unless a certainexibility in each segment permits the segments to come closer togetherwhen such a position is required. It has been discovered, however, thatthe flexibility of materials, such as steel, that are ordinarilyemployed for such applications and the tolerances of hinges 14 permitthe segments 12 to assume such a position without a noticeable change inthe ramp dimensions.

The ramp in its at rest position shown by FIG. 8 the links 64V aresubstantially parallel since each of the segments 12a through 12g aresubstantially parallel. In FIG. 9, however, the ramp is shown in itsfree floating position as where in contact with an uneven truck floorand each segment is stepped down from its adjacent segments and yet isconnected to the adjacent segments through the links 64 though thesegments are no longer aligned.

Rams 26 are hydraulically operated cylinders that are attached to theflanges 36 of the sections 12e and 12e of the ramp segments 12 by meansof a pair of anges 74 which are attached to supporting plates 76, whichare in turn attached to flanges 36 of segments 12e and 12e and alsothrough eye members 82 attached to the rear of ram-s 26. Eye members 82project between the flanges 74 where they are pivotally secured to theflanges 74 by pins 78. The plungers 94 of each ram 26 are attached tosimilar bracket members which are composed of flanges 88 which areattached to support plates 90 which are in turn attached to bottomplates 46 of sleeve members 38 of the segments 120 and 12e. A pin 92projects through perforations in the flanges 88 and eyes (not shown) inthe plungers 94 of rams 26. It may be seen that when the plunger arms 94are extended as shown in FIG. 5 the sleeve members 38 of segments 12eand 12e and, since all the sleeve members 38 of the segments 12 areconnected by links 64, all of the sleeve members 38 of segments 12athrough 12g are similarly extended. Links 64 will pivot only up and downand consequently will not pivot for horizontal movement of the sleevemembers 38 in respect to members 28. Consequently, all of the sleevemembers 38 will slide uniformly when plunger arms 94 of rams 26 areextended or retracted. It may be seen that when plunger arms 94 of rams26 are extended or retracted sleeve members 38 will all be extended orretracted by deck plate 40 and bottom plate 46 sliding on angle slidebars 56, 52, 54 and 55. rIhe slide bars may, of course, be lubricated tofurther reduce friction. Deck plates 3@ and 48 provide a uniformplatform surface in either the extended or retracted position of theramp since cover plates 39 follow deck plates 49 so as to cover the gapbetween deck plates 30 and 40 when the sleeve members 38 are extended.

The power means employed to raise and lower the overall ramp structureconsists of a bumper beam 96 which is powered to rise by two hydrauliccylinders 98. The plungers 189 of cylinders 98 are pivotally attached tothe beam 96 through a pivotal connection 18'4- to the end portion ofstabilizer arms 112. The bottom of the hydraulic cylinders are pivotallyattached to the bottom of the dock pit 11 (see FIG. 4) as by flanges 183that are rigidly attached to the bottom of pit 11 rby any conventionalmeans (in the present instance these cylinders and flanges are attachedto the bottom of the pit by the means taught in United States Patent2,714,735). A pin 188 projects through perforations in the bracketiianges 183 and eye members (not shown) attached to the bottom of thehydraulic cylinders 9S.

The beam 96 is prevented from falling into the pit by stabilizing meanswhich consists of two pivotally mounted stabilizer arms 112 mounted onthe bottom of segments 12b and 121. The arms 112 are provided withpivotal connections consisting of flanges 129 that are attached tosupporting plates 121 which are in turn attached to bottom iianges 36 ofsegments 12b and 12). Flanges 120 contain perforations through whichpins 122 project. Pins 122 also project through perforations (not shown)in arms 112 which extend between the flanges 120 so that these arms arepivotally connected to the nonextending portion of the ramp 10. Arms 112are rigidly attached to beam 96 as by welding (not shown). Hence, uponextending plungers 100 beam 96 will rise ascribing an arc while arms 112pivot at flanges 12.0 while the beam 96 contacts the bottom of sleevemembers 38 of all the segments 12 to elevate the ramp 10. It will beobserved that if the ramp 1t) is lowered until lips 56 `contact a truckiioor the beam may be retracted into the ramp pit (see FIG. 9) and theramp or segments are supported only at the dock 20 by hinge 14 and bythe truck floor (not shown) and consequently is, in this even, a freeiioating loading ramp. On the other hand beam 96 may be raised at anytime to contact the ramp and support it even while the ramp is in use sothat in this instance the ramp is self supporting.

When rams 26 are activated to extend rods 94 and sleeve members 38, thesleeve members 38 slide over beam 96 on the extensions or slide surfaces48 of side members 42 and 44 of the sleeve members 38 so as to minimizefriction that would occur if the larger surfaces of bottom plates 46 ofthe sleeve members 38 were to slide over the beam 96.

When the ramp 10 is not in use it is supported not only by the hydrauliccylinders 98 but also by a lock leg assembly comprising lock legs 121,which in the present embodiment consists of two solid rectangular barswhich rest on a support rest (I beams 123 that are anchored to thebottom of pit 11) when the ramp is in its at rest position (see FIGS. 4and 8). The lock legs 121 are provided with guard plates 125 and arepivotally connected to the bumper beam 96 by means of connecting llanges127 which are attached to bumper beam 96 and angle members 129 which arerigidly attached to lock legs 121 but are pivotally mounted toconnecting members 127 as at 131. Lock legs 121 are pivotally connectedto the sleeve members 38 of segments 12b and 12j respectively by meansof pivot arms which are pivotally mounted to the bracket plates 66 ofthe respective segments 12b and 12j as shown at 137. The Pivot arms 13Sare pivotally mounted at their other ends to projecting bolts attachedto the inner surfaces of lock legs 121. Accordingly when the sleevemembers 38 of the segments 12a-12g are extended by the extension of theplungers 94 of the rams 26 the lock legs 121 are lifted from the lockleg supports 123 since the pivot arms 135 are attached to sleeve members38 of the segments 12b and 12)c while the angle members 129 arepivotally mounted as at 131 to a connecting member 127 attached to thebumper beam 96 which does not extend with sleeve members 3S (see FIG.5). Accordingly the lock legs 121 pivotally swing towards the horizontalposition when the sleeve members 38 are extended and cannot interferewith the free iloating features of the ramp. Of course,

whenever the ramp 10 is elevated the lock legs 121 will lift from theangle beans 123 whether or not the sleeve members 38 are extended. Thepurpose of lock legs 121 are to provide the ramp with extra solidsupport While the ramp is in its retracted and lowered at rest positionand avoid the possibility of a break in the continuity of the dock floor18 and the ramp surface caused by the ramp 10 being slightly lowered orraised.

Two guard plates 141 (FIG. l) are attached to the bottom plates 46 ofsegments 12a and 12g to provide a specific contact or wear surface forbumper beam 96 when the ramp 11D is being raised or lowered by the beam96. Such plates provide more even contact between the bumper beam 96 andthe bottom of segments 12a and 12g since the beam 96 does not extend tocontact the outermost slide surface 48 of the sleeves 38 and if plates141 Were not provided the segments 12a and 12g would be unevenlysupported when the ramp was in contact with the bumper beam 96.

FIGS. 1i) and ll are diagrammatic and schematic drawings of a system tooperate and control the hydraulic cylinders and the rams 26 so as toeffect a safe, easy and systematic control and operation of the ramp ofthe present invention. The operation and control syssystem of FIGS. l0and 1l does not constitute a part of the present invention but is theinvention of another. This system is presently set forth to illustratean operative and preferred control system (particularly the automaticfeatures) it being understood that other systems may be employed inconjunction with the present ramp and the present claims are in no waylimited to the embodiments of FIGS. l0 and ll.

In the schematic drawing of FIG. l0` it may be seen 7 that electricmotor 200 is a three phase 220 volt motor which is supplied by electricpower by the leads 262, 204 annd 206. Motor 200 operates pump 208 (seeFIG. 11) which supplies hydraulic pressure from the reservoir 210 to therams 26 and/cr the hydraulic cylinders 98. The motor 200 runs only whenswitches 212, 21d and 2id (FIG. are closed and these switches are allmechanically linked and are operated by solenoid 218 in the mannerhereafter described. The circuit for the operation of the solenoids andlimit switches operate on 110 volts A.C. power. The electric supplybeing taken from the leads 262 and 266 as at 219 and 220. The 220 volt AC. current is then conducted through a transformer 2i1 to step down thevoltage and provide 110 volt A.C. current to the system. A centralizedpanel (not shown) mounted conveniently adjacent to the ramp exhibitsfour buttons and a single light (although such panels obviously mayexhibit other control lights). The four buttons are labeled Up, Down, Inand Out and operate as shown in FIGS. 10 and 11. Assuming the ramp to bein its at rest position (FIGS. 4 and S) when the Up button is depressedswitches 222 and 224 are closed. Closing of switch 224- completes acircuit to solenoid 213 which closes switches 212, 214 and 216 andstarts the motor 200 to operate pump 263 which supplies hydraulicpressure to hydraulic line 226. At the same time the closing of switch222 completes a circuit to relay 228 which closes switches 230 and 232and opens switch 234. The closing of switches 23h and 232 completescircuits to solenoids 236 and 23S which operate valves 240 and 242respectively (FIG. ll) which permits hydraulic fluid supplied by pump268 to ow into hydraulic cylinders 98 in back of the pistons 246 so asto cause plungers 106' to elevate the ramp l0. The opening of switch 234serves to assure that power will not be supplied to an automatic controlsystem when the ramp is in its free oating position as will hereafter bedescribed. As soon as the ramp commences to move upward from its at restposition a limit switch 248 is released and closes allowing the Down, Inand Out pushbuttons to be operable as will hereinafter be described.

After the ramp has raised to the desired height (above the truck bed),the operator releases the Up button deenergizing relay 22S and openingthe switches 236 and 232 causing solenoids 236 and 238 to close valves240 and 242 permitting no further hydraulic tluid to ow into cylinders98 but since no fluid may escape from the cylinders the ramp at thispoint remains stationary. Switch 234 closes so that automatic featuresof the ramp may take over as soon as the ramp 10 cornes to its freeoating vposition and switch 224 opens to deenergize solenoid 218 andstop motor 200.

The operator may now depress the Out button which completes a circuit tosolenoid 218 by closing switch 25) and activates solenoid 252 by closingswitch 254 (limit switch 248 as described above is closed). Solenoid2318 restarts motor 29) to supply hydraulic fluid while solenoid 252operates valve 255 (FIG. 11) so as to propell piston 256 to the right sothat hydraulic lines 226 and 258 are contiguous with passageway 264 ofthe valve and hydraulic fluid may ilow to the back of pistons 266 of therams 26. Meanwhile hydraulic uid from the front portion of ram 26 mayescape through hydraulic lines 268, through passageway 270 of valve 255to hydraulic line 262 wherein it returns to reservoir 210 forrecirculation. Hence, it is seen that the rams 26 extend their plungers94 which, as has been shown extends the sleeve members 38 of thesegments 12 of ramp 10. When the Out button is released, of course, theswitches 250 and 254 open and accordingly solenoids 218 and 252 aredeenergized, motor 269 stops and valve 255 returns to its originalposition shutting of tlow of hydraulic fluid to and from rams 26 and thesleeve members 3S of ramp ll@ become lstationary.

The yramp now, presumably is extended over the truck bed far enough toassure proper contact and the operator may depress the Down buttonwhich, as shown in FlG. 10, closes switch 272 and, since limit switch24S is closed, energizes relay 279 which closes switches 276 and 275 andopens switch 235. By closing switches 276 and 278 solcnoids 282 and 28dare energized to open valves 236 and 28S to permit hydraulic iluid toflow from hydraulic cylinders 9S through return line 262 and back toreservoir 210, thus lowering the ramp. The operator continues to keepthe Bown button depressed as the ramp makes contact with the truck bed.The support beam 96 continues moving downward until it is approximately1/2 inch below the ramp (or other predetermined distance), where limitswitch 294i is released. This limit switch breaks the circuit of theDown pushbutton, denergizing relay 279 to open switches 276 and 278 andcause solenoids 232 and 2345 to close valves 236 and 283 respectivelyand the hydraulic cylinders 98 will not permit bumper beam 95 to fallfurther. Also, the deenergizing of relay 279 causes switch 236 to closeand the Vopening of limit switch 2% causes switch to close so that thecircuit to lightZg is Icompleted and light 2% lights up. Also, currentis supplied to the conductor 293. Light 294 is the i'loat indicatinglight, telling the operator that the ramp is in automatic free-floatingposition. ln this position only the Up button will remove the ramp fromautomatic float since the' limit switch 296 renders all circuits of theDown, In and Out solenoids inoperative and energization of conductor 29Sactivates the automatic iloat features 296 which may be denergized onlyby means of opening switch 234 which, as heretofore described, opensonly when the Up button is depressed.

It will be observed that the automatic float system will not beoperative unless light 294 is lit. The automatic oat system showngenerally at 296 operates by means of a series' of limit switches 309,362, 394 and 3% and solenoids 236, 23S, 232 and 284 which control thehydraulic valves Zeil, 242, 2% and 288 which, in turn, effect theraising and lowering of bumper beam 96. rl'he limit switches 30d and364- are mounted near one end of bumper beam 96 (disposed to operate inconjunction with segment 22a) and limit switches 32 and 366 are mountedon the other end of the beam (disposed to operate in conjunction withsegment 12g). The limit switches 3th?, 362, 364 and 306 are illustratedby small rectangles in FIG. 9. If limit switch 366 is released due to arise in segment 12a it closes completing a circuit to solenoid 236 whichis energized to open valve 240. At the same time when switch Sii@ closesswitch 308 closes, completing a circuit to solenoid 21S starting motor2th) operating pump 20S to supply hydraulic fluid to one of thehydraulic cylinders 98 (nearest to segment 12a) but not the othercylinder 98 and the beam rises until it is 1/2 inch below the ramp (orwhatever clearance the limit switch is preset to effect). At this pointlirnit switch 365B is again encountered, deenergizing solenoids 236 and218 turning oit the pump motor 209 and hydraulic pressure to thehydraulic cylinder 98. lf segment 12a moves downward toward the beam sothat there is less than the 1/2 inch distance (or the pre-set distance)between the segment )12a and `the beam 96, :lim-it switch 364 .isencountered and closed. This energizes solenoid 282 which controls downvalve 286 which permits hydraulic tluid to escape from the one hydrauliccylinder 98 and allows that end of the bumper beam 96 to move downwardlyuntil it is once more 1/2 inch below the segment 12a. At this point thelimit switch 304 is released, deenergizing solenoid 282 which allows nomore pressure to be released from the single hydraulic cylinder 98 andthe beam remains stationary. It may be observed that limit switches 302and 306 on the other end of beam 96 perform the same function as limitswitches 36@ and Stift. lf limit switch 362 and its accompanying switch3l@ close to energize solenoids 218 and 238 to operate valve 24132 andextend the hydraulic cylinder 9S on the right hand side of the bumperbeam 96 until the set spacing between the bumper beam 96 and the segment12g is reached wherein the limit switch 302 (and switch 310) open todeenergize the solenoids 218 and 238 and stabilize the beam 95. On theother hand it the beam 96 comes too close to segment 12g the limitswitch 396 is closed to activate solenoid 284 which (as shown in FIG.ll) opens valve 283 to permit a lowering of the beam until the properlimit (in this case 1/2 inch) is again attained whereupon the circuit isbroken by the limit switch 366 and the beam is stabilized.

FIG. 9 shows the ramp 1t? in its free oat position and in automaticoperation with the segment 12a being higher than the segment 12g (seeFIG. 9) and yet the bumper beam 96 maintains its proper spacedrelationship to these segments. For the purpose of simplification locklegs 121 and associated components are omitted `from FIG. 9. If thetruck should accidentally pull away from the loading dock during loadingoperations the ramp will drop onto the beam 96. The ramp can drop nomore than the predetermined set distance (i.e. 1/2 inch).

When the truck has been loaded or unloaded, the operator again depressesthe Up button. Depression of the Down, In or Out button has no elect forthese pushbuttons are rendered inoperable when the ramp is in free floatposition, as previously described. When the Up button is depressed relay228 is again energized and, as previously described, this closesswitches 230 and 232 to activate the solenoids 236 and 238 and raise thebeam 96. Switch 234 opens simultaneously to insure deenergization of theautomatic [features 296 of the circuit that raises and lowers the rampand assures that manual operation is complete. Also, as the beam 96moves into contact with the ramp lll limit switch 294i closes andreactivates the In, Out and Down buttons and simultaneously opens switch292 to maintain deactivation of the automatic features 296 of the systemafter the Up button is released. In addition, the lloat light 2942 goesout .and all four pushbuttons are free to perform their associatedfunctions.

The operator continues to depress the Up button until the ramp 1@ islifted away from the truck bed. At this point he releases the Up buttonto deenergize relay 223 and as previously described arrests furtherupward movement of the ramp.

The operator now depresses the In button closing switch 312 to energizesolenoid 21S to supply hydraulic pressure and simultaneously closesswitch 314 to energize solenoid 316. Solenoid 316, as shown by FIG. ll,throws slide valve 255 to the left so as to mesh passage way 318 with`hydraulic line 258 and hydraulic line 262 to permit hydraulic lluid toliow out of rams 26 in back of the pistons 266 while `passageway 320meshes with hydraulic lines 26S and 226 to permit hydraulic fluid tollow into the front portion of the rams 26 and force the plungers 266rearward. The effect is a retraction of the plungers 94 which, aspreviously described, retracts the sleeve members 38 of the segments 12and an overall constriction of the length of the ramp 10. The operatorcontinues to depress the In button until limit switch 322 opens breakingthe circuit to solenoid 316 and causing the piston 256 of valve S toretract to its original position shutting oil the inlets and exists torams 26. Limit switch 322 is mounted on either the `sleeve members 3S orI beam members 2S and is disposed to contact a member (in the presentinstance flange 88) on the other such member so as to arrest theretraction of the sleeve members 38 preferably at a position where whenthe ramp is lowered the legs 121 will contact beams 123 and the rampwill be in its at rest position. The operator next depresses the Downpushbutton energizing relay 279 which, as previously described,energizes solenoids 282 and 284 that operate valves 286 and 288 thatlower the ramp. The

`ramp 10 moves downward until the lock legs 121 are in ltir-m contactwith the support beams 123. At this point limit switch 248 opens whichonce again permits only up movements from this the horizontal retractedor at rest position.

Limit switches 394 and 396 are closed when the ramp is in its at restposition but are inactive because the switch 292 is open. These switchesremain closed when the ramp rises since the bumper beam 96 is rincontact with them, however switch 292 remains open until the bumper beam96 falls free of the ramp whereupon the switch 292 closes activating theautomatic features 296, however, at this time the switches .304 and 366open and the ramp is under automatic control.

As an additional safety feature limit switch 324 is incorporated in thelock leg assembly. When a truck with a floor below dock level is beingloaded, the loading ramp 10 is in a position such that it is extendedand below dock level 18. If the operator raises the ramp only slightlyand begins to retract it while the ramp is still below dock level, thelegs 121 will come into contact with the beam 123 in its other thanvertical position. Damage to the lock leg assembly or legs 121 mayresult; however, limit switch 324 is positioned to encounter one of thebeams 123 to deactivate the relay 279 through switch 326 (mechanicallylinked yto switch 324-) and deactivate the Down circuit. Simultaneouslythe opening of switch 324 deactivates the In button. Thereafter theoperator must move the ramp either out or up until the limit switch 324is released. This feature assures that no damage can be done to the legs121, 4the beams 123 or their associated components. The ramp cannot befully retracted unless it is raised to a height slightly above thehorizontal.

When the ramp 1li is elevated while the segments and beam 96 are in aposition such as is shown by HG. 9 (while the ramp is in automatic freefloating) as controlled by circuit 296, since the elevating pressureoriginates from a single source (hydraulic line 226) the pressure in thecylinders 93 will equalize levelling the ramp. Such cylinders willequalize leveling the bumper beam 96 and hence, the ramp segment-s 12 assoon as the bumper beam contacts the segments 12 after the Up button isdepressed.

The check valves 281 and 233 prevent the hydraulic cylinders 98 lfromlowering the ramp in case of failure of hydraulic pressure when thevalves 241i and 242 are open.

An additional limit switch 325 (FIG. l0 only) is located in a manner toopen when the sleeves 38 of the segments 12 are extended a predetermineddistance. This switch deactivates solenoid 252 which, as previouslydescribed, causes the plungers 94 of cylinders 26 to extend. The switchprevents overextension or extension beyond the limits of the rams 26 anddo not deactivate the ln, Up or Down circuits.

It will be appreciated that the ramp of FlGS. l through 9 is thepreferred embodiment of the present invention in that it combines all ofthe present novel features into a single ramp that is capable ofutilization as a self supporting ramp Where the bumper beam 96 issupporting the ramp structure or it may be a free floating ramp wherethe bumper beam 96 disenga-ges the ramp when it is in contact with avehicle lloor. Also, the segmented features enables the ramp to followthe vehicle to avoid irregularities where the vehicle floor is uneven.The sleeve arrangement provides a strong versati-le extensible featurethat is inherently stronger :and more level than the prior knownextensible platforms of this type. It will also be appreciated that eachof the aforementioned features constitutes invntion in itself and thefollowing claims are not limited to the specific detailed embodiment setforth though the combination of features of this embodiment alsoconstitutes invention.

It is to be noted that the attachment means for joining the variousparts of the ramp 1li may be any of the conventional methods used tojoin such structural compoents. Since the structural members aregenerally manufactured from steel such attachment generally will be bymeans of welding.

I claim:

1. A loading ramp for bridging the gap between a loading dock and avehicle comprising:

(a) a platform made up of a plurality of spaced parallel arms, each saidarms being hinged along one end to said loading dock;

(b) slide members positioned on each of said arms and disposed to slideinwardly and outwardly on said arms so as to extend beyond the free endof said arms when extended outwardly and increase the length of saidplatform;

(c) linking means pivotally connecting each said slide member with itsadjacent slide member and disposed to permit each said adjacent slidemember and its associated arm to move upwardly and downwardly in respectto one another for a predetermined distance while connecting said slidemembers so that they slide inwardly and outwardly on said armssubstantially uniformly;

(d) power means for raising and lowering said arms and slide members and(e) power means for sliding said slide members inwardly and outwardly onsaid arms.

2. A loading ramp for bridging the gap between a loading dock and avehicle comprising:

(a) a platform made up of a plurality of spaced parallel arms, each saidarms being hinged along one end to said loading dock;

(b) a slide member positioned on each said arm and disposed to slideinwardly and outwardly on said arms so as to extend beyond the free endof said arms when extended outwardly and increase the length of saidplatform;

(c) linking means comprising at least one link member positioned betweeneach said slide member and its adjacent slide members and said linkmember being pivotally mounted to each said adjacent slide members andbeing disposed to pivot upwardly or downwardly so that said slidemembers and arms may move up and down in respect to one another for thedistance permitted by the said link members while connecting said slidemembers so that they slide inwardly and outwardly on said armssubstantially uniformly;

(d) power means for raising and lowering said arms and slide members and(e) power means for sliding at least one said slide members inwardly andoutwardly on said arms.

3. A loading ramp for bridging the gap between a loading dock and a-fvehicle comprising:

(a) a platform made up of a plurality of spaced parallel arms, each saidarms being hinged along one end to said loading dock;

(b) a sleeve shaped member telescoped over each said arms so as to formadjacent sleeve shaped members, said sleeve shaped members beingdisposed to slide inwardly and outwardly on said yarms so as to increasethe length of said platform when extended outwardly;

(c) linking means pivotally connecting each said sleeve shaped memberswith their adjacent sleeve shaped members and disposed to permit eachsaid adjacent sleeve shaped members and their associated arms to moveupwardly and downwardly in respect to one another for a predetermineddistance while connecting said sleeve shaped member so that they slideinwardly and outwardly on said arms substantially uniformly;

(d) power means for raising and lowering said arms and sleeve shapedmembers and (e) power means for sliding said sleeve shaped membersinwardly and outwardly on said arms.

4. A loading ramp for bridging the gap between a loading dock and avehicle comprising:

(a) a platform made up of a plurality of spaced parallel arms, each saidarms being hinged along one end to said loading dock;

(b) a sleeve shaped member telescoped over each said arms so as to formadjacent sleeve shaped members, said sleeve shaped members beingdisposed to slide inwardly and outwardly on said arms so asv to increasethe length of said platform when extended outwardly;

(c) linking means comprising at least one link member positioned betweeneach said sleeve shaped member and its adjacent sleeve shaped membersand said link member being pivotally mounted to each said adjacentsleeve shaped members and being disposed to pivot upwardly or downwardlyso that said sleeve shaped members and arms may move up and down inrespect to one another for the distance permitted by the said linkmembers while connecting said sleeve shaped members so that they slideinwardly and outwardly on said arms substantially uniformly;

(d) power means for raising and lowering said arms and sleeve shapedmembers and (e) power means for sliding at least one said sleeve shapedmembers inwardly and outwardly on said arms.

5. A loading ramp for bridging the gap between a loading dock and avehicle comprising;

(a) a platform made up of a plurality of spaced parallel arms, each saidarms being hinged along one end to said loading dock;

(b) a sleeve shaped member telescoped over each said arms so as to formadjacent sleeve shaped members, said sleeve shaped members beingdisposed to slide inwardly and outwardly on said arms so as to increasethe length of said platform when extended outwardly;

(c) linking means pivotally connecting each said sleeve shaped memberwith its adjacent sleeve shaped member and disposed to permit each saidadjacent sleeve shaped member and its associated arm to move upwardlyand downwardly in respect to one another for a predetermined distancewhile connecting said sleeve shaped member so that they slide inwardlyand outwardly on said arms substantially uniformly;

(d) means for raising and lowering said arms and sleeve shaped memberscomprising ian elongated member positioned transversally beneath saidarms and sleeve shaped members, at least one stabilizing arm pivotallyconnecting said elongated member to said arms, power means disposed toraise and lower said elongated member and raise or lower said sleeveshaped members and associated arms and said sleeve shaped members beingdisposed to slide over said elongated member and said elongated memberbeing disposed to disengage said sleeve shaped members when said sleeveshaped members co-ntact said vehicle and (e) power means for slidingsaid sleeve shaped members inwardly and outwardly on said arms.

6. A loading ramp for bridging the gap between a loading dock and aVehicle comprising:

(a) a platform made up of a plurality of spaced parallel arms, each saidarms being hinged along one end to said loading dock;

(b) a sleeve shaped member telescoped over each said arms so as to formadjacent sleeve shaped members, said sleeve shaped members beingdisposed to slide inwardly and outwardly on said arms so as to increasethe length of said platform when extended outwardly;

(c) linking means comprising at least one link member positioned betweeneach said sleeve shaped member and its adjacent sleeve shaped membersand said link member being pivotally mounted to each said adjacent slidemembers and being disposed to pivot upwardly or downwardly so that saidsleeve shaped members and arms may move up and down in respect to oneanother for the distance permitted by the said link members whileconnecting said sleeve shaped members so that they slide inwardly andoutwardly on said arms substantially uniformly;

(d) means for raising and lowering said arms and sleeve shaped memberscomprising an elongated member positioned transversally beneath saidarms and sleeve shaped members, at least one stabilizing arm pivotallyconnecting said elongated member to said arms, power means disposed toraise and lower said elongated member and raise or lower said sleeveshaped members and associated arms and said sleeve shaped members beingdisposed to slide over said elongated member and said elongated memberbeing disposed to disengage said sleeve shaped members when said sleeveshaped members contact said vehicle and (e) power means for sliding atleast one said sleeve shaped members inwardly and outwardly on said xarms.

' 7. A loading ramp for bridging the gap between a loading dock and avehicle comprising:

(a) a platform made up of a plurality of spaced parallel arms, said armsbeing hinged along one end to said loading doek;

(b) a sleeve shaped member telescoped over each said arms so as to formadjacent sleeve shaped members, said sleeve shaped members beingdisposed to slide inwardly and outwardly on said arms so as to increasethe length of said platform when extended outwardly;

(c) linking means comprising at least one link member positioned betweeneach said sleeve shaped member and its adjacent sleeve shaped membersand said link member being pivotally mounted to each said adjacentsleeve shaped members and being disposed to pivot upwardly or downwardlyso that said sleeve shaped members and arms may move up and down linrespect to one another for the distance permitted by the said linkmembers while connecting said sleeve shaped members so that they slideinwardly and outwardly on said arms substantially uniformly;

(d) means for raising and lowering said arms and sleeve shaped memberscomprising an elongated member positioned transversally beneath saidsleeve shaped members, at least one hydraulic cylinder pivotallyconnected to said elongated member and the oor beneath said ramp, atleast one stabilizing arm rigidly connected to said elongated member andeach said stabilizing arm being pivotally connected to one of said armsso that upon the extension of the plungers of said hydraulic cylinderssaid elongated member will rise to contact the bottom of said sleeveshaped members and elevate said ramp and when said hydraulic cylindersare retracted said elongated member and ramp will be lowered so thatwhen said ramp contacts a vehicle said elongated member may disengagesaid sleeve shaped members and ramp but will remain connected to theramp by said stabilizing arms in an upright position, said sleeve shapedmembers being disposed to slide over said. elongated member and (e)power means for sliding at least one said sleeve shaped members inwardlyand outwardly on said arms and over said elongated member.

References Cited by the Examiner UNITED STATES PATENTS 2,527,653 10/50Pierce 1471 2,624,251 1/53 Porter 94-50 2,689,965 9/54 Fenton 14-712,714,735 8/55 Watson 14-71 2,881,457 4/59 Rodgers 14-71 2,881,458 4/59Rodgers 14-71 2,909,970 10/59 Jackson 94--48 2,993,219 7/61 Pennington14-71 FOREIGN PATENTS 814,162 3/37 France.

JACOB L. NACKENVOFF, Primary Examiner,

1. A LOADING RAMP FOR BRIDGING THE GAP BETWEEN A LOADING DOCK AND AVEHICLE COMPRISING: (A) A PLATFORM MADE UP OF A PLURALITY OF SPACEDPARALLEL ARMS, EACH SAID ARMS BEING HINGED ALONG ONE END TO SAID LOADINGDOCK; (B) SLIDE MEMBERS POSITIONED ON EACH OF SAID ARMS AND DISPOSED TOSLIDE INWARDLY AND OUTWARDLY ON SAID ARMS SO AS TO EXTEND BEYOND THEFREE END OF SAID ARMS WHEN EXTENDED OUTWARDLY AND INCREASE THE LENGTH OFSAID PLATFORM; (C) LINKING MEANS PIVOTALLY CONNECTING EACH SAID SLIDEMEMBER WITH ITS ADJACENT SLIDE MEMBER AND DISPOSED TO PERMIT EACH SAIDADJACENT SLIDE MEMBER AND ITS ASSOCIATED ARM TO MOVE UPWARDLY ANDDOWNWARDLY IN RESPECT TO ONE ANOTHER FOR A PREDETERMINED DISTANCE WHILECONNECTING SAID SLIDE MEMBERS SO THAT THEY SLIDE INWARDLY AND OUTWARDLYON SAID ARMS SUBSTANTIALLY UNIFORMLY; (D) POWER MEANS FOR RAISING ANDLOWERING SAID ARMS AND SLIDE MEMBERS AND (E) POWER MEANS FOR SLIDINGSAID SLIDE MEMBERS INWARDLY AND OUTWARDLY ON SAID ARMS.